A number of minimal access tools that may be controlled by a user's hand are known, such, as for example, U.S. Pat. No. 8,668,702 and U.S. patent application Ser. No. 14/166,503. These devices may include a frame, an input joint that provides two orthogonal rotations between a handle and the frame, a tool shaft that is connected to the frame, an output joint that provides two orthogonal rotations between the tool shaft and an end-effector, and a means (such as a transmission system) to transmit the two orthogonal rotations of the input joint to the output joint. These devices are exceptionally useful, and may allow highly dexterous control (e.g., articulation) of tool connected to the output joint at the end of the elongate shaft. In general, devices such as those described in U.S. Pat. No. 8,668,702 typically secure the frame directly to the arm of the user, and more generally the frame is typically attached to the forearm of the user. An example of an apparatus as taught in U.S. Pat. No. 8,668,702 is shown in FIGS. 1-3.
In these examples, the frame may be an extended structure that is rigidly connected to the tool shaft on one end and a forearm attachment member on the other end. The forearm attachment member interfaces with the forearm using a variety of means including Velcro, straps, etc. The forearm attachment may connect comfortably yet securely, i.e. to constrain, and therefore transmit, all degrees of freedom (DoF) or motions between the forearm and the forearm attachment member. Some relative motion may still be allowed to ensure comfort. As used herein, “forearm” may refer to the distal end of the arm, e.g., distal to the elbow and just before the wrist joint, as illustrated in FIG. 4.
This kind of arrangement may decouple two rotational DoF (pitch and yaw) associated with the wrist and one open/close DoF associated with thumb/fingers from the four DoF available at the forearm: three translations and 1 roll rotation. FIG. 5 illustrates the three orthogonal translations at the forearm. FIGS. 6A-6C show the roll rotation of a forearm (pronation/supination). The remaining two rotations associated with the wrist joint are also shown in FIGS. 7A-7B and 8A-8B. FIGS. 7A and 7B illustrate pitch rotation of the wrist joint (e.g., radial and ulnar deviation). FIGS. 8A and 8B illustrate yaw rotation of the wrist joint (flexion/extension). FIG. 9 shows additional illustrations of the rotational motions associated with the forearm and the wrist joint.
In these examples, note that the DoF are cumulative; i.e., there are four DoF available at the forearm; the wrist-joint provides another two; therefore, at the hand (palm), there are 6 DoF. There are additional DoF associated with the fingers/thumb. These include open/close motion, which was discussed in U.S. Pat. No. 8,668,702. These may also include other motions such as twirling and pecking, which will be described further below.
The forearm attachment described in U.S. Pat. No. 8,668,702 transmits 4 DoF at the forearm (three translations) and one roll rotation to the instrument shaft distal end, independent of the wrist rotations and finger/thumb closure motion. This may be accomplished because the forearm is attached to the frame via the forearm attachment member, and therefore the four motions at the forearm translate to the frame and then to the shaft and to the distal end of the shaft. Separately, an input joint, which may be configured as a virtual center (VC) mechanism, and may be employed to capture the two rotations of the wrist joint of the user. These two are then transmitted via a mechanical transmission comprising cables that are routed via the common ground (i.e. the frame and the tool-shaft) of the input joint and output joint (end-effector articulating join). As described in U.S. Pat. No. 8,668,702, the transmission system may be any general transmission system and not simply one that is based on cables.
Such schemes may allow for a one-to-one (1:1) motion mapping from the user's (e.g. a surgeon's) motion input to the corresponding output motions of a remote end-effector. FIG. 10 illustrates a mapping of the user input motions to the device output motions in this type of system. However, by rigidly attaching the frame to the forearm of the user, making the frame a rigid extension of the forearm, the axis of the instrument (specifically the axis of the shaft) becomes rigidly fixed (or not adjustable) with respect to the axis of the forearm. This may prove to be uncomfortable for the user in a situation when the tool shaft has to point in a certain direction and may require discrete re-adjustment with respect to the forearm during use. A rigid or non-adjustable alignment of the instrument axis with the forearm may not be ergonomically conducive for the user's forearm and shoulder. In one exemplary view in FIG. 11 (showing a side view), the two nearly horizontal lines 1101 and 1103 (axis of the device and axis of the forearm) are aligned with each other because of the “rigid” or locked forearm cuff attachment. If the instrument/device (e.g. its shaft) needs to be pointed in a certain direction (shown by line 1105) as may be required by some application (e.g. a surgical procedure), then the forearm will also have to follow the same extended line, which might be uncomfortable for the user's upper arm and shoulder. To correct for this, the device must be manually adjusted (if possible) to modify the angle of the apparatus relative to the user's body. What is needed is a device that may continuously adjust the alignment of the apparatus during use. As described herein, connecting the body part to the frame of the device through one or more coupling joints permitting predetermined degrees of freedom (while constraining others) may allow continuous adjustability.
A similar limitation may arise in the other plane as seen in the top view of FIG. 12. As shown in FIG. 12, the two lines 1201, 1203 (e.g. the axis of the device and the axis of the forearm) are aligned with each other because of the rigid (or locked) forearm cuff attachment. If the instrument/device/tool (e.g. its shaft) needs to be pointed in a direction such as the one shown by line 1205, as required by some applications (e.g. surgical procedures), then the forearm will also have to follow the same extended line, which might be uncomfortable for the user.
Further, attaching the frame rigidly to the forearm may limit the ability to transmit certain motions or DoF associated with the user's fingers, particularly twirling motion and pecking motion which are illustrated in FIGS. 13A-13C and 14A-14B. For example, FIGS. 13A-13C illustrate a hand making a twirling motion with an object (e.g., pen). In this example, the forearm and wrist joint do not move while the fingers/thumb produce the twirling motion. FIGS. 14A-14B illustrate a pecking motion. When making a pecking motion, the forearm and wrist joint do not move while the fingers/thumb produce the fore and aft pecking motion. These motions of the fingers/thumb may happen with respect to the wrist joint and forearm, but when the frame (and therefore tool shaft) is rigidly attached to the forearm, these motions are not directly transmitted to frame, e.g., the tool shaft including the tool-shaft distal end. These motions may be captured and transmitted in an indirect manner, e.g., when using a transmission system that is routed through the tool frame and shaft, as described in the U.S. Pat. No. 8,668,702 patent, in which the two wrist motions and the fingers/thumb open/close motion are captured and transmitted to corresponding output motion of an end-effector at the distal end of the tool shaft. Similarly, the pecking motion of the fingers/thumb may be translated to a similar motion between the handle and the tool frame (when the user holds the handle in his hand, fingers, and thumb); this relative motion between the handle and tool frame may be captured via a transmission system (e.g. a cable or other transmission system between the frame and distal end of the tool shaft) and transmitted to a corresponding motion between the end-effector and distal end of the tool shaft. Similar transmission may be conceived for the twirling motion as well. However, when the tool frame is secured to the forearm via a forearm attachment member, the yaw and pitch rotations of the hand/wrist or the twirling and pecking motion of the fingers/thumb/hand are not directly transmitted to the tool shaft distal end. As used herein, “direct” transmission means a transmission that may be achieved by virtue of a geometric extension as opposed to via a “transmission system” that comprises multiple components that move relative to each other.
Described herein are methods and apparatuses that may address the problems and goals discussed above. In particular, described herein are wrist and/or forearm attachment devices, and/or apparatuses such as tools and systems including these forearm attachment devices, that may allow for direct transmission of additional motions such as pecking and twirling motions.
The methods and apparatuses described herein may achieve these advantages by providing a coupling between a body portion, e.g., a wrist and/or a forearm, and a frame so that the body portion may be moved through one or more degrees of freedom relative to a portion of the frame.